Just had two hubs fail (came right off ) but mine were severely neglected by the prior owner. I picked up new caps from Waymire Distribution 317-631-7551. PART # 0583OU ( oil BRG Cap New Style) $30 each. The new style cap does not have a outside O ring . They recommend some RTV on the seam when you tap them in. Make that bang them in ! I cleaned out the bearings but didn't not remove mine. I did read up a little and I saw some guys that had this issue due to a bent axel ? I replaced all four of my caps and no leaks so far.